<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS选择器-交集选择器</title>
    <style>        
        p{
            color: red;
        }
        /* 交集选择器 */
        p.par{
            color: blue;
        }
    </style>
</head>
<body>
    <p>文字</p>
    <p class="par">文字</p>
    <div class="par">文字</div>
</body>
</html>